1. Field of the Invention
The present invention relates to a light emitting device that uses a semiconductor laser as a light source.
2. Related Art
Today, there are light emitting devices each having a light emitting diode as a semiconductor light emitting element, and each of the light emitting devices is designed to emit light uniformly within the device. By a known technique, for example, a reflecting mirror is provided near a light emitting diode, so as to adjust the light traveling direction and the spatial distribution of the light density. By another known technique, a light diffusion agent as well as a fluorescent substance is contained in a sealing agent that guides the light from a light emitting diode, and the diffused reflection is utilized. By yet another known technique, the spatial distribution of light density is adjusted by changing the shapes of the incident face and the emission face of the light guiding body (see Japanese Patent No. 3,991,961 and JP-A 2006-32370 (KOKAI), for example). Also, there is a known technique by which a sealing agent having a high refractive index is used to efficiently re-extract the light from a fluorescent substance and direct the light toward the emission face side (see JP-A 2007-27751 (KOAKI), for example).
However, any of those techniques is based on the principles of light reflection and transmission. By any of those techniques, a certain ratio of transmission light and a certain ratio of reflected light are not used for light emission from light emitting devices. Therefore, the transmission light and reflected light cause loss, and a high light emitting efficiency is not achieved.